From Huai-Ti Lin, Gary G. Leisk, and Barry Trimmer of the Departments of Biology and Mechanical Engineering at Tufts University:

[S]ome caterpillars can curl into a wheel and generate their own rolling momentum as part of an escape repertoire. This change in body conformation occurs well within 100 ms and generates a linear velocity over 0.2 m s?1, making it one of the fastest self-propelled wheeling behaviors in nature.

Their paper is available for free from IOPscience for 30 days, with registration. ScienceNOW has video of the model organism, and the model behavior, that inspired this impressive means of locomotion. [Thanks, Alan Dove!]

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and makezine.com. My work has also appeared in ReadyMade, c’t – Magazin für Computertechnik, and The Wall Street Journal.

“…over 0.2 m s−1, making it one of the fastest self-propelled wheeling behaviors in nature”

let’see… on: http://en.wikipedia.org/wiki/Wheel_spider we see: 44turns/s, and we’ll presume “Wheel spiders are up 20 millimeters in size” is a diameter so… pi*20mm*44rps -> 2765 mm/s or 2.8m/s, an order of magnitude faster. of course the caterpillar does it from a dead stop and on the flat.